Circuit interrupter



| R. LUDWIG E-rAL 2,525,494

` CIRCUIT INTERRUPTER Original Filed Nov. 11, 1942 oct. 10,1950

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yand, more particularly, 'structures therefor.

ksion of our copending application, Serial No.

Patented Oct. 10, 1950 `UNITED .STATES PATENT OFFICE-.pv

*CIRCUIT INTERRUPTER Leon R. Ludwig, Wilkinsburg, Benjamin P. Baker,

Turtle Creek, .and Winthrop M. Leeds, Wilkinsburg, Pa., ass'ig'nors to Westinghouse Electric Corporation, la corporation of Pennsylvania LOriginal application November 11, `1942, Serial No.

465,244. Divided and this application Decem ber 22, Y1945, Serial No. 636,941

l This invention relates to circuit interrupters, to arc extinguishing This application is a divi- 465,244, med November 11, 1942 new United rStates Patent 2,405,469, issued August 27, 1946.

More specifically our invention relates to a novel structure for effecting the very rapid extinction of electric arcs drawn in circuit interrupters. It is particularly applicable to the interruption of high voltage arcs, such vas those drawn in a 287 kv. circuit, 4and will effect their interruption in less than one cycle. Our invention is, however, not limited in its application only to high voltage circuits. It is also Aapplicable on low voltage circuits, but merely forv purposes of illustration it is described in the specication in a preferred embodiment as used on a lhigh voltage circuit.

Extensive experimental investigation has clearly'demonstrated that a rapid lowering oi the dielectric strength of an arc extinguishing fluid, such as oil, occurs after it 'impinges uron n the arc stream. It is therefore desirable to .eliminate such contaminated fluid as quickly as possible, and to subject the arc stream `to the action of fresh, iiuid of high dielectric strength. It is one of the objects of our invention to provide an arc extinguishing structure which makes i'ull use of this fact.

Another object is to provide an improved arc extinguishing structure which will direct a plurality of spaced jets of arc extinguishing fluid at the arc and will permit the venting of such jets at a number of spaced intermediate points along .unbalanced forces acting upon the Voperating mechanism.

`Further objects and advantages will readily become apparent upon a reading. of the following description taken in conjunctionv with the drawings, in which: Y

4 Claims. (Cl. 20D-150) Figure 1 is aside elevational vView in crosssection of a circuit interruptor embodyingour invention and shown in the closed-circuitposition;

lFig. 2 is a side velevational view in cross section taken on the line IIL-II of Fig. 1, but showing the interruptor in the partiallyopen circuit position; and

Fig. 3 is a plan view in cross section taken along the line IlI-III of Fig. l.

Referring to the drawing., and more particularly to Fig. 1 thereof, it will be observed vthat we have provided an interrupting unit having a resiliently mounted relativelystationary contact ||8 cooperating with a rod-shaped movable contact U9. 7A metallic tubular guide |29 is .provided to guide the movement of the relatively stationary contact H8. A line terminal connection |2| is made at the upper end of the guide |20. Y y A `tubular insulating casing |22 is provided, Within which reciprocally moves a piston V.|23 preferably made of insulating material. A compression spring |24 biases the piston |23 downwardly as viewed in Fig. l. Movable with th`e piston |23 is a tubular insulating member |25 at the upper end of which is threadedly secured a metallic plate or ring |26 which slides over the guide member |20. T'hreadedly secured to the lower end of the guide member |20 is aninsulating arcing chamber |21 formed in this instance from a single piece of insulating material. A plurality of inlet passages or iluid channels, in this instance four, are provided 'being designated by the reference numerals |28. A plurality of vent passages |29, in this instance four, are provided leading from shallow `openings or pockets |41', the disposition of which 4are more' clearly shown in Fig. 3. Between each inlet passage |28 and each vent passage |29 is an annular oil pocket or recess l|"3|"which serves to retain yfresh oil` adjacent the arc 3| which is drav/nduring the opening operation when the movable contact ||9 is ywithdrawn downward away from the relatively stationary ycontact ||8. Not only do the oil pockets or recesses |30 retain. fresh oil or other arc extinguishing iiuid adjacent to the arc |3|, but also they provide a corrugated arc passage which prevents the arc lf3 from contacting insulation sur-faces during its elongation..

The arcing chamber or extinguishing means |21 has openings formed therein to provide flu-id v conducting passages |48. These interconnect to |32 which duiing the opening operation serves to close an annular aperture |33 in the lower portion of the piston |23.

Secured rigidly to the movable contact I I9 is a sleeve |34 having a perforated disk |35 integrally formed therewith, the purpose for which will appear more fully hereinafter. A stop ring |36 is provided at the lower end of the tubular insulating casing |22 to limit the downward travel of the piston |23.

The operation of the interrupter will now be described. In operation, the tubular insulating casing |22 is completely immersed in a suitable arc extinguishing iiuid, such as oil. When it is desired to open the circuit passing through the interrupter, the movable contact ||9 is drawn downward. The relatively stationary contact I8 follows the initial downward movement of the movable contact I9 until the washer |37 strikes the top of the guide |20. At this point, the movable contact ||9 separates from the relatively stationary contact ||8 to draw an arc |3|, more clearly shown in Fig. 2. Meanwhile, the compression spring |24 has forced the piston |23 downward within the casing |22 to move with it the tubular insulating member |25 and the metallic ring |26. The oil disposed in the region |38 is compressed and forced to fiow downward into the inlet passages |28, as indicated by the arrows |39. The oil forced to flow into the inlet passages |28 contacts the arc |3| and flows thereafter through the oil pockets |30 to be vented through the vent passages |29, as designated by the arrows in Fig. 2.

During the interruption of low currents, the compression spring |24 provides the necessary biasing force to move the piston |23 downward and hence displacing the oil in the region |38 so as to cause it to flow into the inlet passages |28. During the interruption of high currents, the piston |23 and the ring |26 cooperate to constitute a differential piston. Thus, the surface area of the ring |26 is less than the surface area of the piston |23. Therefore, the net force tending to move the piston |23 downward will cooperate with the compression spring |24 to cause, on the interruption of high currents, increased fluid fiow from the region |38 into the inlet passages |28 to contact the arc 3|. It will be apparent that the arc |3| acts on the piston |23 through the vent passages |29, and that the arc |3| acts on the metallic ring |26 through the inlet passages |28.

The resulting movement of the oil causes rapid extinction of the arc |3|. It will, therefore, be apparent that in this embodiment of our invention we have devised a structure which utilizes the arcing pressure in conjunction with a difierential piston to assist arc interruption during the interruption of high currents.

Referring particularly to Fig. 3, it will be noticed that the inlet passages |28 communicate with an enlarged annular region or shallow open ing or pocket |4| which insures that the now directed into the interrupting arc |3| will be radially thereof about the periphery of the arc stream |3|. It will be noted that the portion of the arc passage between a pocket 4| and a pocket |41 may be termed a recessed orifice portion |49 as indicated on the drawing, the recessing arising by virtue of the presence of the pockets |30. The passage structure is partly described and claimed in our copending application filed December 22, 1945, Serial Number 636,940,

now United States Patent 2,467,760, issued April 19, 1949, to us, and assigned to the assignee of the instant invention.

During the opening operation, the sleeve |34 surroundingfthe movable Contact ||9 and movable therewith permits the washer |32 to close the annular aperture |33 in the piston |23. During the closing of the interrupter, the sleeve |34 strikes the washer |32 to raise the latter and permit fluid to flow out through the annular aperture |33 to permit quick closing of the interrupter.

Although we have illustrated a specific embodiment it will be clearly understood that the same was merely for the purpose of illustration and that changes and modifications may be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

We claim as our invention:

l. A circuit interrupter including means for establishing an arc, arc extinguishing means of insulating material forming an arc passage for the arc closely confining the arc along a major portion of its length, said arc extinguishing means defining at least two shallow openings along the arc passage larger than the opening of the arc passage to thereby provide a plurality of pockets at spaced intervals along the arc passage, said arc extinguishing means having other openings therein on at least opposite sides of said arc passage to provide fluid conducting passages, the arc extinguishing means being slotted between the iiuid conducting passages to provide fluid channels to at least one of said pockets, said arc extinguishing means being slotted from at least another of the pockets to the opposed external surfaces of the arc extinguishing means to provide venting passages from said other pockets, and the walls of the arc passage having at least one recess between adjacent pockets to provide fresh iiuid along the arc passage and also to break up the insulation surfaces to minimize the possibility of voltage breakdown axially along the are passage.

2. A circuit interrupter including means for establishing an arc, arc extinguishing means of insulating material for defining a substantially enclosed arc passage of insulating w material closely conning the arc along a major portion of its length, said arc extinguishing means defining a recessed orifice portion within the arc passage, the arc extinguishing means defining a pair of diametrically positioned inlet passages on one level so that an incoming flow of iiuid may pass through the inlet passages inwardly toward the arc substantially transversely thereto on opposite sides thereof, said arc extinguishing means forming a venting passage therein positioned on move in a direction to force liquid toward the arc to extinguish the same, and means associated with the movable Contact for picking up the diiferential piston on the closing stroke oi the interrupter to charge the s-ame against the biasing force exerted by the biasing means.

4. A circuit interrupter including a substanm tially enclosed interrupting unit, a movable dif ferential piston member having larger and smaller surface areas exposed to the arcing pressure, the larger surface area of the movable dierential piston member constituting one outer movable wall of the interrupting unit, an opening provided in said movable outer wall of the interrupting unit, means for establishing arcing within the interrupting unit including a rod-shaped movable contact movable along the opening, means biasing the differential piston to move in a direction to force liquid toward the arc to extinguish the same, valve means associated with the opening, and means associated with the REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,899,612 Dyer Feb. 28, 1933 1,955,214 Whitney et al Apr. 17, 1934 2,061,945 Koppelmann et al. Nov. 24, 1936 2,235,901 Ronnberg Mar. 25, 1941 2,292,547 Sadler Aug. 11, 1942 2,304,529 Baker Dec. 8, 1942 

